UPSTREAM: firmware: arm_ffa: Setup in-kernel users of FFA partitions

Parse the FFA nodes from the device-tree and register all the partitions
whose services will be used in the kernel.

In order to also enable in-kernel users of FFA interface, let us add
simple set of operations for such devices.

The in-kernel users are registered without the character device interface.

Link: https://lore.kernel.org/r/20210521151033.181846-5-sudeep.holla@arm.com


Tested-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
(cherry picked from commit d0c0bce8)
Change-Id: I05ad9200f2821c48e617ebdfc65f20651c3c1b35
Bug: 168585974
Signed-off-by: Will Deacon <willdeacon@google.com>